You end up learning lots of cleaning tricks as an Interior Designer.  The Magic Eraser is always in our tool-kit, but unfortunately, it can end up removing your wall paint along with your smudge.  Use this trick to avoid that problem when you need to clean almost anything off of your walls, from magic marker to a shoe smudge:

Elemental Clean Tip 1: TOOTHPASTE!  Apply a bit of toothpaste to a wet rag and scrub your wall clean.  You’ll be amazed.